A cellular telecommunications system is a communication system that is based on the use of radio access entities and/or wireless service areas. The access entities operate over respective coverage areas that are typically referred to as cells. Examples of cellular telecommunications systems include standards such as GSM (Global System for Mobile communications) or various GSM based system (such as GPRS (General Packet Radio Service)), AMPS (American Mobile Phone System), DAMPS (Digital AMPS), WCDMA (Wideband Code Division Multiple Access), UMTS (Universal Mobile Telecommunications System), CDMA 2000 and so on.
In a cellular system, a base transceiver station provides a wireless communication facility that serves mobile stations (MS) or similar wireless user equipment (UE) via an air or radio interface within the coverage area of the cell.
GSM is a so called second generation system which is widely used. UMTS is a so called third generation system and it is envisaged that in the future UMTS may replace GSM. However, at the moment GSM and UMTS systems co-exist. Some user equipment, but not all, is able to communicate both with UMTS systems and GSM systems.
The third generation partnership project (3GPP) has been setting out aspects of the UMTS system. It has standardised a mechanism to cope with the fact that some user equipment which have previously been provided may contain some faulty behaviour. A so called bit map architecture option has been selected as the mechanism for achieving this.
In this regard, reference is made to the 3GPP standard TS 23.195 (version 5.3.0) which specifies the functionality for this feature. The core network is arranged to delivery user equipment specific behaviour information (UESBI) over the Iu interface to the RNC (radio network controller) which can then adapt its functionality with respect to the malfunctioning user equipment. The UESBI-Iu is derived from the user equipment's international mobile equipment identity with software version (IMEISV) which is requested from the user equipment using a specific MM (mobility management) procedure at location updating. In particular, the used MM procedure is the MM identity request.
With the currently proposed standard, the MSC/MSS (mobile switching centre/MSC server) needs to retrieve the IMEISV from the user equipment when the location update is done over the Iu- or the A-interface. The A-interface is between MSC/MSS and BSC (GSM/2G architecture At the moment UESBI-Iu is utilized only by UTRAN according to 3GPP TS 23.195, i.e. when the UE has a connection over the Iu-interface. However, retrieval of IMEISV over the A-interface too is required due to possible inter-system handover from GSM to UMTS during a call. This is valid when a call is established in GSM radio access, and when inter-system handover to UMTS occurs, then the MSC controlling the call should have the IMEISV of the UE.
However, the mechanism currently proposed has a problem. According to TS 23.195, the IMEISV needs to be obtained from the user equipment in every circuit switched IMSI (international mobile subscriber identity) Attach and Inter-VLR (visitor location register) Normal Location Updating procedure. The MM identity request procedure needs to be performed, as discussed above, when the IMSI Attach and Normal Location Updating mode takes place over the A interface and for examples occurs in a MSC/MSS which is serving only a GSM BSS (base station system). On the other hand, the UESBI-Iu can only be sent over Iu interface and is thus usable only for UMTS purposes only.
At the moment the number of user equipment that are able to provide GSM access only as compared to the number of user equipment that are capable of providing UTMS access is very large. It is envisaged that this situation is likely to continue for a number of years. Thus, the currently proposed procedure involves the MM identity request procedure being performed unnecessarily, because for a UE capable of GSM radio access only the inter-system handover is not possible. This is undesirable.
Accordingly, it is an aim of embodiments of the present invention to address this problem.